QCD Evolution of Superfast Quarks

Abstract

Recent high-precision measurements of nuclear deep inelastic scattering at high x and moderate 6 < Q${}^2$ < 9GeV${}^2$ give a rare opportunity to reach the quark distributions in the {\it superfast} region, in which the momentum fraction of the nucleon carried by its constituent quark is larger than the total fraction of the nucleon at rest, x>1. We derive the leading-order QCD evolution equation for such quarks with the goal of relating the moderate-Q${}^2$ data to the two earlier measurements of superfast quark distributions at large 60 < Q${}^2$ < 200~GeV${}^2$. Since the high-Q${}^2$ measurements gave strongly contradictory estimates of the nuclear effects that generate superfast quarks, relating them to the high-precision, moderate-Q${}^2$ data through QCD evolution allows us to clarify this longstanding issue. Our calculations indicate that the moderate-Q${}^2$ data at $x\lesssim 1.05$ are in better agreement with the high-Q${}^2$ data measured in (anti)neutrino-nuclear reactions which require substantial high-momentum nuclear effects in the generation of superfast quarks. Our prediction for the high-Q${}^2$ and x>1.1 region is somewhat in the middle of the neutrino-nuclear and muon-nuclear scattering data.

8 pages and 5 figures, version to appear in Physical Review D 99, 114019

References in corpus (7)

• nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties in the CTEQ framework
• EPPS16: Nuclear parton distributions with LHC data
• New Results on Short-Range Correlations in Nuclei
• Final-state interactions in semi-inclusive deep inelastic scattering off the Deuteron
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Cited by in corpus (6)

• The energy-momentum tensor of spin-1 hadrons: formalism
• nCTEQ15HIX -- Extending nPDF Analyses into the High-$x$, Low $Q^2$ Region
• Strong Interaction Physics at the Luminosity Frontier with 22 GeV Electrons at Jefferson Lab
• Target mass corrections in lepton--nucleus DIS: theory and applications to nuclear PDFs
• Nuclear medium effects in lepton-nucleus DIS in the region of $x\gtrsim 1$
• Hard processes in multi-TeV ion collisions